As a background art of the present technical field, JP 2013-143202 A (PTL 1) can be mentioned. PTL 1 describes a structure including a circuit board on which an electronic component is mounted and a housing for accommodating the circuit board, wherein the housing has a connector accommodation space that accommodates and fixes a card edge connector for connecting a board connection terminal of the circuit board and an external wire harness, and an accommodation space of the circuit board, an end portion of the circuit board at which the board connection terminal is formed is protruded from the board accommodation space to the connector accommodation space, and is inserted into a board insertion space of the card edge connector, and the board connection terminal is brought into contact with the connector terminal and connected through a spring mechanism provided on a connector side. PTL 1 describes a mechanism in which relative displacement between the circuit board and the card edge connector or the like is avoided even when vibration or external force acting on electronic devices is applied. An example in which phosphor bronze is plated with Ni/Au as a material of the connector terminal is described, but there is no description about a material of the board connection terminal. On the other hand, JP 2006-9126 A (PTL 2) describes a material of the board connection terminal of the circuit board which is connected through the card edge connector. PTL 2 describes that, in a FPC board, a lead-free solder plating layer with a thickness of 0.2 μm to 2.0 μm is formed on a wiring circuit of a connector fitting part, a lead-free solder plating layer with a thickness of 2.0 μm or more is formed on a wiring circuit in a component mounting part of the FPC board to prevent deterioration of wettability due to the growth of Cu—Sn intermetallic compound, and the lead-free solder plating layer is heat-treated at a temperature of 140° C. to 180° C. for 1 hour, or at melting point temperature of solder or more for 0.1 second or more. PTL 2 describes an effect that prevents whiskers growing from a part in contact with the connector terminal in the connector mating part of the FPC board.